connect: Add the envvar GIT_SSH_VARIANT and ssh.variant config

This environment variable and configuration value allow to
override the autodetection of plink/tortoiseplink in case that
Git gets it wrong.

[jes: wrapped overly-long lines, factored out and changed
get_ssh_variant() to handle_ssh_variant() to accomodate the
change from the putty/tortoiseplink variables to
port_option/needs_batch, adjusted the documentation, free()d
value obtained from the config.]

Signed-off-by: Segev Finer <segev208@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: segevfiner

Documentation/config.txt

@@ -1949,6 +1949,17 @@ Environment variable settings always override any matches.  The URLs that are
 matched against are those given directly to Git commands.  This means any URLs
 visited as a result of a redirection do not participate in matching.
 
+ssh.variant::
+	Depending on the value of the environment variables `GIT_SSH` or
+	`GIT_SSH_COMMAND`, or the config setting `core.sshCommand`, Git
+	auto-detects whether to adjust its command-line parameters for use
+	with plink or tortoiseplink, as opposed to the default (OpenSSH).
++
+The config variable `ssh.variant` can be set to override this auto-detection;
+valid values are `ssh`, `plink`, `putty` or `tortoiseplink`. Any other value
+will be treated as normal ssh. This setting can be overridden via the
+environment variable `GIT_SSH_VARIANT`.
+
 i18n.commitEncoding::
 	Character encoding the commit messages are stored in; Git itself
 	does not care per se, but this information is necessary e.g. when

Documentation/git.txt

@@ -1020,6 +1020,12 @@ Usually it is easier to configure any desired options through your
 personal `.ssh/config` file.  Please consult your ssh documentation
 for further details.
 
+`GIT_SSH_VARIANT`::
+	If this environment variable is set, it overrides Git's autodetection
+	whether `GIT_SSH`/`GIT_SSH_COMMAND`/`core.sshCommand` refer to OpenSSH,
+	plink or tortoiseplink. This variable overrides the config setting
+	`ssh.variant` that serves the same purpose.
+
 `GIT_ASKPASS`::
 	If this environment variable is set, then Git commands which need to
 	acquire passwords or passphrases (e.g. for HTTP or IMAP authentication)

connect.c

@@ -694,10 +694,14 @@ static const char *get_ssh_command(void)
 static int handle_ssh_variant(const char *ssh_command, int is_cmdline,
 			      int *port_option, int *needs_batch)
 {
-	const char *variant;
+	const char *variant = getenv("GIT_SSH_VARIANT");
 	char *p = NULL;
 
-	if (!is_cmdline) {
+	if (variant)
+		; /* okay, fall through */
+	else if (!git_config_get_string("ssh.variant", &p))
+		variant = p;
+	else if (!is_cmdline) {
 		p = xstrdup(ssh_command);
 		variant = basename(p);
 	} else {
@@ -717,7 +721,8 @@ static int handle_ssh_variant(const char *ssh_command, int is_cmdline,
 	}
 
 	if (!strcasecmp(variant, "plink") ||
-	    !strcasecmp(variant, "plink.exe"))
+	    !strcasecmp(variant, "plink.exe") ||
+	    !strcasecmp(variant, "putty"))
 		*port_option = 'P';
 	else if (!strcasecmp(variant, "tortoiseplink") ||
 		 !strcasecmp(variant, "tortoiseplink.exe")) {

t/t5601-clone.sh

@@ -401,6 +401,32 @@ test_expect_success 'single quoted plink.exe in GIT_SSH_COMMAND' '
 	expect_ssh "-v -P 123" myhost src
 '
 
+test_expect_success 'GIT_SSH_VARIANT overrides plink detection' '
+	copy_ssh_wrapper_as "$TRASH_DIRECTORY/plink" &&
+	GIT_SSH_VARIANT=ssh \
+	git clone "[myhost:123]:src" ssh-bracket-clone-variant-1 &&
+	expect_ssh "-p 123" myhost src
+'
+
+test_expect_success 'ssh.variant overrides plink detection' '
+	copy_ssh_wrapper_as "$TRASH_DIRECTORY/plink" &&
+	git -c ssh.variant=ssh \
+		clone "[myhost:123]:src" ssh-bracket-clone-variant-2 &&
+	expect_ssh "-p 123" myhost src
+'
+
+test_expect_success 'GIT_SSH_VARIANT overrides plink detection to plink' '
+	GIT_SSH_VARIANT=plink \
+	git clone "[myhost:123]:src" ssh-bracket-clone-variant-3 &&
+	expect_ssh "-P 123" myhost src
+'
+
+test_expect_success 'GIT_SSH_VARIANT overrides plink to tortoiseplink' '
+	GIT_SSH_VARIANT=tortoiseplink \
+	git clone "[myhost:123]:src" ssh-bracket-clone-variant-4 &&
+	expect_ssh "-batch -P 123" myhost src
+'
+
 # Reset the GIT_SSH environment variable for clone tests.
 setup_ssh_wrapper